My hot water heater is old and leaking and I need to replace. I'm not sure about all the copper piping and all. Can you tell me where I should start?

googler - first of all is the hot water tank a gas or electrical 220-volt?? Now to change the tank out and install a new one :: if it is electric _ turn off the power to the tank< next you need to turn off the water to the tank:: next - drain the water out of the tank: connect a water hose to the drain valve on the bottom of the tank< run the hose out side or to a drain: turn the valve open and finish draing the tank ( note- after a little of the water has drained out -open the relief valve so it will drain comply:: while it is draining < remove the electrical from the top of the tank ( remove cover plate so you can:: )n top of the tank where the water is hooked up to the tank there should be a brass nut screwed down holding the pipe in place on the tank:: un screw the (2) nuts and vremove the copper pipes :: now after it gets threw draing the water out <you are ready to remove the tank : you might have to use a two wheel dolly to remove it out side :: now when you get the new tank allso get the new relief valve and the new fittings from the supplier where you get it at :: tell him what you haver at home that the old tank was hooked up to : more then likely it will be !/2 inch copper or 3/4 inch copper
When you have all the items : you can hook the tank back up in reverse of how you took it out : you will also need a can of pipe dope to put on the fittings <to help keep them from leaking. Don't forget the nipples pipe you screw into the top of the tank :: make sure the nipp:es are screwed in tight (do not strip ) and all fittings are tight and the relief valve is tight :: i hope this will help you : if it is gas come back on here and tell me :: if this does help pleas rate my answer << have a good day and god bless ::f.b.e.

googlerr- I forgot to list this ;; when you have the water hooked back to the tank ,go to the kitchen and open the hot water side of the kitchen sink faucet;; Turn the water back on and let the water run from the faucert un till you have a good study flow comeing out ;; tjhis will make sure the tank is full of water and the top heating element is covered with water and won't blow;; After filling the tank turn the power back on ;you may have to adjust the top and bottom thermostate; when there was kids in the house ,I always set the temperature to no more then 120 degrees;;
AGAIN GOOD LUCK :F.B.E.

Also you may have plastic pipe going to your water tanks, or there my not be any unions to unscrew if this is the case you will need to cut the water pipes. If you are not good with sodering the are new fittings called gator bites which work really well and will fit copper or plastic with no sodering required

THanks for the help. I successfully put it in yesterday.This site is awesome.